The present invention relates to a self-attaching cardiac pacer lead and more particularly to such a lead which incorporates means for forming a wire suture which can secure the lead in position.
Various schemes have been proposed for retaining or securing, to heart tissue, the distal end of a flexible cardiac pacer lead. Such a flexible lead is typically employed because it is desirable to locate the pacer circuitry and batteries at a point remote from the heart in order to have more room and so as to facilitate replacement of the pacer upon depletion of its batteries. Some means, e.g., a flexible lead, is thus needed for providing conduction between the pacer's circuitry and the desired stimulation site. Further, some means is needed for securing the distal end of the lead to the desired location, e.g., atrium or ventricle. Among the schemes proposed previously may be noted the use of hooks or barbs; the use of a helical screw-in electrode; and the use of various clamping elements. Such constructions are shown, for example, in U.S. Pat. Nos. 3,416,533; 3,416,534; 3,472,234; 3,754,555; 3,814,104; 3,902,501; and 4,000,745.
While certain of these prior art constructions have met with limited success, there have likewise been certain problems and difficulties associated with different ones of these constructions. In some, the attachment device renders the tip of the lead bulky and increases the difficulty of initially positioning or inserting the lead, particularly where a pervenous approach is used. Particularly with regard to the hooked and barbed type of constructions, the attachment means may cause undue trauma to the heart, resulting in the formation of fibrosis which interferes with the electrical characteristics necessary for satisfactory stimulation. Thus, over time, an increased stimulation threshold is observed.
Among the several objects of the present invention may be noted the provision of a cardiac pacer lead which can be secured to cardiac tissue at the desired point of stimulation; the provision of such a lead which is relatively easily introduced by means of a pervenous approach; the provision of such a lead which, once attached, is relatively secure and yet which does not produce undue trauma to the cardiac tissue due to the means of attachment; the provision of such a pacer lead construction which is reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.